Field of the Invention
The invention relates to a readjustment system in accordance with the preamble of claim 1.
Description of Related Art
Readjustment systems of this type are used, for example, for readjustment in the case of wear of the tool or in the case of precision finishing of inner and outer contours of workpieces, wherein said contours can have a cylindrical, eccentric or out-of-round shape.
DE 10 2007 017 800 A1 discloses a readjustment system in which a spindle supports a membrane tilting head by which a cutting edge is adjustable in the radial direction so as to impart a round, oval and/or trumpet shape in the longitudinal axis of the piston bolt or any other suited shape to a small connecting rod eye, for example. The membrane tilting head is adjusted via, a linearly adjustable actuator, also referred to as tie rod, via which a tool head supporting the cutting edge and being operatively connected to a membrane can be tilted with respect to the spindle axis so as to bring about radial adjustment. The tie rod is supported in the spindle and co-rotates with the same. A rear end portion of the tie rod is guided out of the spindle and is supported there via a bearing arrangement on a slide adjustable via an actuator. In the known solutions the spindle is driven via a drive motor which is arranged in parallel to the spindle axle and is operatively connected to the spindle via a belt drive or the like. For precision finishing of bores the adjusting means has to be configured so that diameter tolerances ≤IT6 can be observed. The roundness, cylindrical shape or straightness of the surfaces to be machined has to reach values up to a maximum of 3μ. Moreover, it must be possible to produce profile shapes and/or defined ovality within the range of few μ.
It is a drawback of said solutions that considerable construction space and efforts in terms of apparatuses are required for the spindle drive and also the bearing of the tie rod. Another drawback consists in the heat transmission through the tie rod.
In DE 44 01 496 C3 an adjusting means for machining round, out-of-round and/or non-cylindrical contours is described in which the adjustment of the cutting edge is performed via a head including piezoelectric translators. In the known readjustment system the head is approximately U-shaped, the piezoelectric actuator being arranged in a fixed leg of the U-shaped head and acting on an elastically deflectable leg at which the cutting edge is retained. By deforming the piezoelectric actuators the elastically deflectable leg and thus the cutting edge can be adjusted in the radial direction. It is a drawback of this solution that the tool holder has to be configured to exhibit elasticity so that especially in the case of high cutting efficiency the quality required for precision finishing cannot be ensured. It is another drawback that the U-shaped tool holder requires considerable construction space. Furthermore it is detrimental that due to the U-shaped tool head an imbalance by which the machining accuracy can be further deteriorated is produced upon readjustment or actuation.